NCGT, Issue 59, June 2011





A critical examination of a range of geophysical and geological evidence exposes the inadequacy of plate tectonics to account for the geological development of the North Atlantic. In an attempt to get out of the present deadlock, the theory of Global Wrench Tectonics (Storetvedt, 1997 & 2003) is applied to account for the physiographic and tectono-magmatic history of the region – with particular emphasis to its late Cretaceous- Tertiary evolution. According to the new theory, the Earth had originally acquired a thick pan-global continental incrustation which subsequently has been subjected to a long history of irregular sub-crustal attenuation and related chemical changes, progressively running towards an oceanic mode – processes that reached its peak during the Upper Mesozoic. On this basis, the multitude of variably submerged micro-continental masses in the North Atlantic – including Iceland and the rest of the Shetland/Greenland Ridge, as well as the occurrences of a large variety of continental rocks recovered from sites along the Mid-Atlantic Ridge, are readily explained. The accelerated loss of crustal material to the mantle during the late Cretaceous gave rise to events of moderate true polar wander (changing the relative position of the equatorial bulge) and increase in the Earth’s rate of rotation – regarded here as the principal dynamical triggers of the Alpine tectonic revolution. Latitude-dependent inertia mechanisms, basically controlled by the Coriolis Effect, led to westward wrenching of the global palaeolithosphere. In this process, the thinned and mechanically weakened North Atlantic lithosphere broke up in ‘mid’-ocean position, giving rise to left-lateral shearing and the general structural obliquity observed along the mid-ocean rift. As constituent parts of the Alpine lithospheric wrenching, Europe and North America underwent relative clockwise rotations in situ, bringing their respective polar paths apart. Hence, the current separation of the polar trails for the two continents does not require lateral continental separation – only relative changes of their azimuths. There is no factual evidence that linear magnetic field anomalies represent the association of geomagnetic polarity changes and isochrones of seafloor evolution as is currently believed. Instead, a variety of evidence suggests that the marine magnetic linearity arises from a combination of fault-aligned magnetomineralogical changes giving rise to susceptibility contrasts and induction from the ambient geomagnetic field. On the new global tectonic basis, the range of physiographic and tectonic features of the North Atlantic is reinterpreted

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